We find that the thermalization process occurs in characteristic stages with clearly separated timescales, depicted in Fig. REF .
At earliest times, \(\epsilon \cdot t \lessapprox 1\) , there is quick change from an initially un-entangled product state, with Schmidt rank \(\chi =1\) , to a state with maximal rank \(\chi = \text{dim} (A)\) . As is illustrated in Fig. REF (a), this phase is characterized by exponential growth of Schmidt values \({P}_\lambda (t)\equiv \exp {(- \xi _\lambda (t) )}\) , reminiscent of unstable mode growth in classical plasmas [1]}.
